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Device
Driver
Header
The
device
driver
header
is
used by
the
HH
0/S
to
verify that
a
file is
a device
driver,
which
device
the
driver
belongs
to,
and
additional control
information
needed
to
install
and
remove
it
The
format
of
the
header
is
as
follows;
Field
Name
Field
Length
Datal
DVRCHK
2
bytes
word
DEVNAM
8
bytes
byte
DVCTRL
2
bytes
word
DVFUNC
2
bytes
word
VECNUM
1
byte
byte
VECTOR
4
bytes
dword
LENGTH
2
bytes
word
Total
length
of
header
=
21 bytes
1.
DVRCHK
-
This
field
is
used by
the
HH
O/S
to verify that
the
file
is
a
device
driver.
It
must
contain the value
5C10h.
2.
DEVNAM
This
field
specifies
the
name
of
the
device
that this
driver
belongs
to.
The
name
must be
in
upper
case,
left
justified
in
the
field,
and padded
with
blanks
to
the
right.
The
following
names
are
legal
and
represent the
complete
set of
devices
for
which a
driver
may
be
defined.
KYBD
LCD
GRPH
CASS
PRN
DSK
COM
BAR
TCH
-
Keyboard
input.
BIOS
INT 50h
-
LCD
Text
output.
BIOS
INT
51 h
-
LCD
Graphics
output.
BIOS
INT
52h
-
Cassette.
BIOS
INT
53h
-
Printer.
BIOS
INT 56h
-
Disk
support.
BIOS
INT
57h
-
Communication/Modem
support.
BIOS
INT
59h
-
Bar
Code
Reader
Support.
BIOS
INT
5Ah
-
Touch
Panel Support.
BIOS
INT
5Bh
3.
DVCTRL
-
This
field
defines the
control entry point of
the device
driver.
This
entry point
will
be
called
when
the device
driver
is
installed,
when
the
HH
O/S
finds
it
necessary
to
move
the
device
driver
to
a
new
location
in
memory, and
when
the device
driver
is
being
removed.
4.
DVFUNC
-
This
is
the device
function entry
point.
This
offset
will
be
placed
in
the
interrupt
vector
when
the device
is
installed.
5.
VECNUM
-
This
1
byte
field
contains the
interrupt
vector
number
of
the vector
used by
the
device.
118
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